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Flight-induced changes in human amino acid excretion.
Aviation, Space, and Environmental Medicine
|January 11, 1976
Summary
Flight stress in aircrew was assessed using urinary analysis during a 96-hour airborne alert. Findings indicate significant stress before flights and adaptation over time, with urea and amino acid excretion as key indicators.
Area of Science:
- Aerospace Medicine
- Human Physiology
- Biochemistry
Background:
- Flight operations, particularly prolonged airborne alerts, can induce physiological stress in aircrew.
- Understanding the biochemical markers of stress is crucial for optimizing crew health and performance.
Purpose of the Study:
- To evaluate the biomedical effects of flight stress on aircrew during a 96-hour airborne alert.
- To identify correlations between urinary excretion markers and physiological stress responses.
Main Methods:
- Urinary determinations were conducted on aircrew members participating in a 96-hour airborne alert mission.
- Crew members were divided into teams operating EC-135J aircraft with varying flight durations (8.5 or 12 hours).
- Preflight baseline data were compared with data collected during and after flights.
Main Results:
- Urea excretion showed a strong correlation with amino acid output.
- Amino acid output, in turn, correlated significantly with alpha-amino nitrogen output.
- Marked anticipatory stress was observed before the alert, significant flight stress occurred late in flights during the first 48 hours, and adaptation to stress was noted in the final 48 hours.
Conclusions:
- Urinary urea, amino acid, and alpha-amino nitrogen levels serve as reliable indicators of flight stress.
- Aircrew experience distinct phases of stress response, including anticipation, acute stress, and adaptation, during prolonged airborne operations.